title: Phenotype of htgA (mbiA), a recently evolved orphan gene of Escherichia coli and Shigella, completely overlapping in antisense to yaaW.
abstract: Overlapping embedded genes, such as htgA/yaaW, are assumed to be rare in prokaryotes. In Escherichia coli O157:H7, gfp fusions of both promoter regions revealed activity and transcription start sites could be determined for both genes. Both htgA and yaaW were inactivated strand specifically by introducing a stop codon. Both mutants exhibited differential phenotypes in biofilm formation and metabolite levels in a nontargeted analysis, suggesting that both are functional despite YaaW but not HtgA could be expressed. While yaaW is distributed all over the Gammaproteobacteria, an overlapping htgA-like sequence is restricted to the Escherichia-Klebsiella clade. Full-length htgA is only present in Escherichia and Shigella, and htgA showed evidence for purifying selection. Thus, htgA is an interesting case of a lineage-specific, nonessential and young orphan gene.
authors.affiliation: Lehrstuhl für Mikrobielle Ökologie, Wissenschaftszentrum Weihenstephan, Technische Universität München, Freising, Germany.
authors.forename: Lea
authors.initials: L
authors.lastname: Fellner
authors.forename: Niklas
authors.initials: N
authors.lastname: Bechtel
authors.forename: Michael A
authors.initials: MA
authors.lastname: Witting
authors.forename: Svenja
authors.initials: S
authors.lastname: Simon
authors.forename: Philippe
authors.initials: P
authors.lastname: Schmitt-Kopplin
authors.forename: Daniel
authors.initials: D
authors.lastname: Keim
authors.forename: Siegfried
authors.initials: S
authors.lastname: Scherer
authors.forename: Klaus
authors.initials: K
authors.lastname: Neuhaus
mesh_terms: D018441:Biofilms; D019295:Computational Biology; D019453:Escherichia coli O157 / Q000235:genetics* / Q000378:metabolism; D029968:Escherichia coli Proteins / Q000235:genetics* / Q000378:metabolism; D019143:Evolution, Molecular; D055786:Gene Knockout Techniques; D006360:Heat-Shock Proteins / Q000235:genetics* / Q000378:metabolism; D055442:Metabolome; D009154:Mutation; D010641:Phenotype; D010802:Phylogeny; D011401:Promoter Regions, Genetic / Q000235:genetics; D012760:Shigella / Q000235:genetics* / Q000378:metabolism; D013045:Species Specificity; D024363:Transcription Initiation Site
chemical_list: D029968:Escherichia coli Proteins; D006360:Heat-Shock Proteins; C080936:yaaW protein, E coli
keywords: functional characterization; htgA-yaaW; overlapping genes